Oral anticoagulants vitamin K antagonists (VKA) have been used for many years in the treatment of thromboembolic disorders, which are among the most costly diseases in terms of public health resources. According to the Agence française de sécurité sanitaire des produits de santé (AFSSAPS), it was estimated at about 900,000 the number of patients treated with VKA in 2008 (more than 1% of the French population). VKA are at the origin of many adverse effects, given their narrow therapeutic window. They are the cause of the death of approximately 5000 patients per year. The use of this therapy is a priority axis of reflection for the Haute Autorité de Santé.